Abstract Bulk-fill composites can be placed at a thickness of 4 mm due to their sufficient depth of cure. The aim of this study was to investigate the effects of bulk versus incremental application methods on the shrinkage vectors and the percentage of volumetric polymerization shrinkage of the composites. Twelve molars were divided into three groups (n = 4), and cylindrical cavities (diameter = 6 mm, depth = 4 mm) were prepared, etched and bonded with OptiBond FL (Kerr). Cavities were restored with a 4-mm bulk-fill composite of Tetric EvoCeram Bulk Fill (TBF, Ivoclar Vivadent) designated as “TBF-bulk”, with two 2-mm increments of a bulk-fill composite designated as “TBF-incremental”, and with two 2-mm increments of a hybrid composite Tetric EvoCeram (TEC, Ivoclar Vivadent) designated as “TEC-incremental”. Each material application was scanned twice in a micro-CT (uncured and cured states), and inherent air bubbles served as markers. Scans were subjected to image segmentation to calculate the shrinkage vectors and the percentage of volumetric polymerization shrinkage. Significantly greater mean values of the shrinkage vectors were observed in “TBF-bulk”, followed by “TBF-increment1”, with no difference between the remaining increments of the groups (ANOVA, Tamhane's T2, p

中文翻译：

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不同应用复合材料的收缩矢量和体积收缩百分比

摘要 由于固化深度足够，散装填充复合材料可以放置在 4 毫米的厚度。本研究的目的是研究体积与增量应用方法对复合材料收缩矢量和体积聚合收缩百分比的影响。十二颗磨牙被分为三组（n = 4），并准备圆柱腔（直径 = 6 mm，深度 = 4 mm），蚀刻并用 OptiBond FL (Kerr) 粘合。使用称为“TBF-bulk”的 Tetric EvoCeram Bulk Fill（TBF，Ivoclar Vivadent）的 4 毫米散装填充复合材料修复腔体，其中两个 2 毫米增量的散装填充复合材料称为“TBF 增量” ，以及两个 2 毫米增量的混合复合材料 Tetric EvoCeram（TEC，Ivoclar Vivadent）被指定为“TEC-incremental”。每个材料应用在微 CT（未固化和固化状态）中扫描两次，并且固有气泡用作标记。对扫描进行图像分割以计算收缩向量和体积聚合收缩的百分比。在“TBF-bulk”中观察到明显更大的收缩向量平均值，然后是“TBF-increment1”，组的剩余增量之间没有差异（ANOVA，Tamhane's T2，p